The price will be really cheap, I think that will round 70€ per person into the rental house I undertake, the rental houses have 300m between them.
About travel info, is like Marcbri said, the best option is flying to Madrid, in the airport (I supose that it will be Barajas's airport) you have to take the underground to go to the ''Méndez Álvaro - Estación Sur'' bus station and there take the bus to Cuenca.
http://img715.imageshack.us/img715/1723/metrodemadrid.gif
Madrid's bus station:
ESTACION SUR DE AUTOBUSES DE MADRID
Est. Sur de Autobuses - Avda. Mendez Alvaro, 83
Tlf.: (+34)915396302
Cuenca's Bus Station
CUENCA
C/ Fermin Caballero, 20 - Est. de Autobuses
Tlf.: (+34)969221184
Here to buy the bus.
http://www.venta.avanzabus.com/compra/busqueda.jsp
And then we you will be in Cuenca we can contact and I'll go in my car or at foot.
Come!!